NYU Observational Astronomy 2013-2014

2a1046385e6cf8e4d07d590f9821ece5?s=47 federica
June 17, 2015

NYU Observational Astronomy 2013-2014

Class II
- the scientific method
- earth's rotation and its origin and consequences

2a1046385e6cf8e4d07d590f9821ece5?s=128

federica

June 17, 2015
Tweet

Transcript

  1. lecture 2 the scientific method - earth’s motion observational astronomy

    1
  2. lecture 2 the scientific method - earth’s motion recap R.A.

    / Dec: tied to the object, never changes H.A. / Dec: tied to the observer/object Alt. / Az : tied to the observer Other systems: •Ecliptic •Galactic Other Concepts: •Ecliptic •Local Sidereal Time 2
  3. lecture 2 the scientific method - earth’s motion recap R.A.

    / Dec: tied to the object, never changes H.A. / Dec: tied to the observer/object Alt. / Az : tied to the observer Other systems: •Ecliptic •Galactic Other Concepts: •Ecliptic •Local Sidereal Time NCP Celestial Equator NP SP Eq •Vernal Equinox R.A. Decl. SCP 3
  4. lecture 2 the scientific method - earth’s motion recap R.A.

    / Dec: tied to the object, never changes H.A. / Dec: tied to the observer/object Alt. / Az : tied to the observer Other systems: •Ecliptic •Galactic zenith nadir C.E. NP SP Eq Horizon NORTH Alt. Other Concepts: •Ecliptic •Local Sidereal Time 4
  5. lecture 2 the scientific method - earth’s motion goals: •familiarize

    with and orient yourself in the night sky •understand (and predict!) basic observable astronomy phenomena •understanding the scientific method 5
  6. lecture 2 the scientific method - earth’s motion goals: •familiarize

    with and orient yourself in the night sky •understand (and predict!) basic observable astronomy phenomena •understanding the scientific method 6
  7. lecture 2 the scientific method - earth’s motion 7

  8. lecture 2 the scientific method - earth’s motion 8

  9. lecture 2 the scientific method - earth’s motion 9

  10. lecture 2 the scientific method - earth’s motion 10

  11. lecture 2 the scientific method - earth’s motion 11

  12. lecture 2 the scientific method - earth’s motion 12

  13. lecture 2 the scientific method - earth’s motion 13

  14. lecture 2 the scientific method - earth’s motion 14

  15. lecture 2 the scientific method - earth’s motion 15

  16. lecture 2 the scientific method - earth’s motion everyone was

    an astronomer Two things fill the mind with ever new and increasing admiration and awe, the more often and steadily we reflect upon them: the starry sky above me and the moral law within me. Aristotle 350 BC Plato 380 BC ... Kant 1755 16
  17. lecture 2 the scientific method - earth’s motion everyone was

    an astronomer Two things fill the mind with ever new and increasing admiration and awe, the more often and steadily we reflect upon them: the starry sky above me and the moral law within me. Aristotle 350 BC Plato 380 BC ... Ptolemy 150 BC Copernicus 1500 Kepler 1600 Kant 1755 Galileo 1650 17
  18. lecture 2 the scientific method - earth’s motion the earth

    is round, and it orbits around the sun 18
  19. lecture 2 the scientific method - earth’s motion the earth

    is round, and it orbits around the sun the earth is round, and it orbits around the sun 19
  20. lecture 2 the scientific method - earth’s motion http://en.wikipedia.org/wiki/File:Ptolemaicsystem-small.png Peter

    Apian, Cosmographia, Antwerp, 1524 from Edward Grant, "Celestial Orbs in the Latin Middle Ages", Isis, Vol. 78, No. 2. (Jun., 1987). Geocentric models are natural: from our perspective we see the Sun moving, while we stay still the earth is round, and it orbits around the sun 20
  21. lecture 2 the scientific method - earth’s motion As observations

    improve this model cannot fit the data anymore! not easily anyways... http://en.wikipedia.org/wiki/File:Cassini_apparent.jpg Source Encyclopaedia Brittanica 1st Edition Author Dr Long's copy of Cassini, 1777 the earth is round, and it orbits around the sun 21
  22. lecture 2 the scientific method - earth’s motion A new

    model fit the data “naturally” (for now anyways...) http://en.wikipedia.org/wiki/File:Copernican_heliocentrism_diagram-2.jpg Image of heliocentric model from Nicolaus Copernicus' "De revolutionibus orbium coelestium". the earth is round, and it orbits around the sun 22
  23. lecture 2 the scientific method - earth’s motion A new

    model fit the data “naturally” (for now anyways...) Image of heliocentric model from Nicolaus Copernicus' "De revolutionibus orbium coelestium". http://en.wikipedia.org/wiki/File:Pluralitas.jpg Okham’s razor: "Pluralitas non est ponenda sine necessitate" John Duns Scotus (1265–1308) http://en.wikipedia.org/wiki/File:Copernican_heliocentrism_diagram-2.jpg the earth is round, and it orbits around the sun 23
  24. lecture 2 the scientific method - earth’s motion prescription for

    a scientific theory: • favor the models that require fewer parameters 24
  25. lecture 2 the scientific method - earth’s motion prescription for

    a scientific theory: • favor the models that require fewer parameters • a scientific theory must be provable 25
  26. lecture 2 the scientific method - earth’s motion prescription for

    a scientific theory: • favor the models that require fewer parameters • a scientific theory must be provable falsifiable 26
  27. lecture 2 the scientific method - earth’s motion everyone was

    an astronomer Two things fill the mind with ever new and increasing admiration and awe, the more often and steadily we reflect upon them: the starry sky above me and the moral law within me. Aristotle 350 BC Plato 380 BC ... Popper 1934 Ptolemy 150 BC Copernicus 1500 Kant 1755 Galileo 1650 Kepler 1600 The Logic of Scientific Discovery 27
  28. lecture 2 the scientific method - earth’s motion prescription for

    a scientific theory: • favor the models that require fewer parameters • a scientific theory must be falsifiable • most scientific theories are actually based largely on probabilistic induction and modern inductive inference (Solomonoff, frequentist vs Bayesian methods...) 28
  29. lecture 2 the scientific method - earth’s motion the earth

    is round, and it orbits around the sun Image of heliocentric model from Nicolaus Copernicus' "De revolutionibus orbium coelestium". http://en.wikipedia.org/wiki/File:Copernican_heliocentrism_diagram-2.jpg 29
  30. lecture 2 the scientific method - earth’s motion earth’s motion

    30
  31. lecture 2 the scientific method - earth’s motion timelaps -

    1 hour steps 31
  32. lecture 2 the scientific method - earth’s motion timelaps -

    1 hour steps 32
  33. lecture 2 the scientific method - earth’s motion timelaps -

    1 day steps 33
  34. lecture 2 the scientific method - earth’s motion earth’s spin

    http://www.weatherscience.net/ 34
  35. lecture 2 the scientific method - earth’s motion earth’s rotation

    www.bradfreese.com 35
  36. lecture 2 the scientific method - earth’s motion ref: infinity

    imagined 36
  37. lecture 2 the scientific method - earth’s motion 37

  38. lecture 2 the scientific method - earth’s motion orbit of

    the earth I. sidereal time 38
  39. lecture 2 the scientific method - earth’s motion orbit of

    the earth I. sidereal time 39
  40. lecture 2 the scientific method - earth’s motion orbit of

    the earth solar day = 24h 40
  41. lecture 2 the scientific method - earth’s motion sidereal day

    = 23h 56m orbit of the earth 41
  42. lecture 2 the scientific method - earth’s motion sidereal day

    = 23h 56m orbit of the earth the RA transiting at a given standard time advances by about 4 minutes per day 4 min/day 2 hours/month 24 hours / 12 months 42
  43. lecture 2 the scientific method - earth’s motion orbit of

    the earth LST: local sidereal time is the RA of the meridian at zenith in a given place at a given time 43
  44. lecture 2 the scientific method - earth’s motion orbit of

    the earth LST = H.A. + RA LST: local sidereal time is the RA of the meridian at zenith in a given place at a given time 44
  45. lecture 2 the scientific method - earth’s motion orbit of

    the earth LST = H.A. + RA LST: local sidereal time is the RA of the meridian at zenith in a given place at a given time ALSO LOOK UP: Universal time Local time Mean Solar time Greenwich time Daylight saving time... 45
  46. lecture 2 the scientific method - earth’s motion orbit of

    the earth II. “the ever changing sky” 46
  47. lecture 2 the scientific method - earth’s motion orbit of

    the earth 47
  48. lecture 2 the scientific method - earth’s motion Stars in

    this direction visible at night orbit of the earth 48
  49. lecture 2 the scientific method - earth’s motion six month

    later... orbit of the earth 49
  50. lecture 2 the scientific method - earth’s motion Stars in

    this direction visible at night orbit of the earth 50
  51. lecture 2 the scientific method - earth’s motion 51

  52. lecture 2 the scientific method - earth’s motion 52

  53. lecture 2 the scientific method - earth’s motion 53

  54. lecture 2 the scientific method - earth’s motion 54

  55. lecture 2 the scientific method - earth’s motion 55

  56. lecture 2 the scientific method - earth’s motion 56

  57. lecture 2 the scientific method - earth’s motion 57

  58. lecture 2 the scientific method - earth’s motion 58

  59. lecture 2 the scientific method - earth’s motion 59

  60. lecture 2 the scientific method - earth’s motion 60

  61. lecture 2 the scientific method - earth’s motion 61

  62. lecture 2 the scientific method - earth’s motion 62

  63. lecture 2 the scientific method - earth’s motion 63

  64. lecture 2 the scientific method - earth’s motion 64

  65. lecture 2 the scientific method - earth’s motion 65

  66. lecture 2 the scientific method - earth’s motion 66

  67. lecture 2 the scientific method - earth’s motion 67

  68. lecture 2 the scientific method - earth’s motion 68

  69. lecture 2 the scientific method - earth’s motion visibility and

    latitude Stars in this direction visible from this latitude “horizon” “horizon” “zenith” North North equator 69
  70. lecture 2 the scientific method - earth’s motion visibility and

    latitude 70
  71. lecture 2 the scientific method - earth’s motion visibility and

    latitude 71
  72. lecture 2 the scientific method - earth’s motion visibility and

    latitude 72
  73. lecture 2 the scientific method - earth’s motion visibility and

    latitude 73
  74. lecture 2 the scientific method - earth’s motion visibility and

    latitude 90o 74
  75. lecture 2 the scientific method - earth’s motion 150 million

    km Perihelion 147.09 x 106 km Aphelion 152.10 x 106 km (only 3% difference!) orbit of the earth 75
  76. lecture 2 the scientific method - earth’s motion Equator ecliptic

    angle = 23.4 deg angle between the orbital plane of the earth and equator orbit of the earth III. axis tilt 76
  77. lecture 2 the scientific method - earth’s motion orbit of

    the earth NCP NeclipticP 23.4o SCP 77
  78. lecture 2 the scientific method - earth’s motion orbit of

    the earth NCP NeclipticP SCP summer solstice winter solstice 23.4o 78
  79. lecture 2 the scientific method - earth’s motion Summer Solstice

    Jun 20 Autumnal Equinox Sep 23 Winter Solstice Dec 21 H.A. = 0 @ midnight? Vernal Equinox March 21 79
  80. lecture 2 the scientific method - earth’s motion RA =

    18h RA = 0h RA = 6h Summer Solstice Jun 20 Autumnal Equinox Sep 23 Winter Solstice Dec 21 RA = 12h Vernal Equinox March 21 80
  81. lecture 2 the scientific method - earth’s motion RA =

    18h RA = 0h RA = 6h Summer Solstice Jun 20 Autumnal Equinox Sep 23 Winter Solstice Dec 21 RA = 12h Vernal Equinox March 21 81
  82. lecture 2 the scientific method - earth’s motion RA =

    18h RA = 0h RA = 6h Summer Solstice Jun 20 Autumnal Equinox Sep 23 Winter Solstice Dec 21 RA = 12h Vernal Equinox March 21 82
  83. lecture 2 the scientific method - earth’s motion RA =

    18h RA = 0h RA = 6h Summer Solstice Jun 20 Autumnal Equinox Sep 23 Winter Solstice Dec 21 RA = 12h Vernal Equinox March 21 83
  84. lecture 2 the scientific method - earth’s motion seasons 84

  85. lecture 2 the scientific method - earth’s motion seasons December

    21 (southern hemisphere summer) 85
  86. lecture 2 the scientific method - earth’s motion seasons June

    21 (northern hemisphere summer) 86
  87. lecture 2 the scientific method - earth’s motion seasons December

    21 (northern hemisphere winter) 87
  88. lecture 2 the scientific method - earth’s motion seasons December

    21 (southern hemisphere summer) • earth is closer to the sun • solar cycles • changes in magnetic field of the earth 88
  89. lecture 2 the scientific method - earth’s motion seasons December

    21 (southern hemisphere summer) • earth is closer to the sun • solar cycles • changes in magnetic field of the earth • other 89
  90. lecture 2 the scientific method - earth’s motion 150 million

    km Perihelion 147.09 x 106 km Aphelion 152.10 x 106 km (only 3% difference!) seasons 90
  91. lecture 2 the scientific method - earth’s motion seasons December

    21 (southern hemisphere summer) • sun radiation incident at a perpendicular angle • longer days: sun radiation integrated for longer time • less atmospheric dispersion 91
  92. lecture 2 the scientific method - earth’s motion SUN equator

    NP 92
  93. lecture 2 the scientific method - earth’s motion equator NP

    SUN winter solstice 93
  94. lecture 2 the scientific method - earth’s motion equator NP

    SUN summer solstice 94
  95. lecture 2 the scientific method - earth’s motion equator SUN

    equinox SP NP SP 95
  96. lecture 2 the scientific method - earth’s motion equator tropic

    of cancer tropic of capricorn antarctic circle arctic circle what is the declination of the sun? SUN 96
  97. lecture 2 the scientific method - earth’s motion equator what

    is the declination of the sun? tropic of cancer tropic of capricorn antarctic circle arctic circle RA Dec -90d 90d 24h 0h SUN ...homework... 97
  98. lecture 2 the scientific method - earth’s motion but why

    all this rotation??? 98
  99. lecture 2 the scientific method - earth’s motion Each star

    that forms has a disk of hydrogen and helium (and heavier elements) surrounding it. Within this disk, planets form. 99
  100. lecture 2 the scientific method - earth’s motion Each star

    that forms has a disk of hydrogen and helium (and heavier elements) surrounding it. Within this disk, planets form. 100
  101. lecture 2 the scientific method - earth’s motion Each star

    that forms has a disk of hydrogen and helium (and heavier elements) surrounding it. Within this disk, planets form. 101
  102. lecture 2 the scientific method - earth’s motion Minor Planet

    Center: http://minorplanetcenter.net/ 102
  103. lecture 1 overview - coordinates summary 1.The modern epistemological paradigm

    is based on falsifiability (and simplicity) 2. Celestial bodies are in continuous motion: the earth spins, revolves, the galaxy rotates, the local group moves ... 3.The Earth’s spin causes celestial bodies apparent daily motion 4. The hour circles moves 4 min/day due to the rotation of the Earth around the Sun changing the night sky landscape seasonally 5. The ecliptic is tilted 23.4o from the Earth’s equatorial plane 6. Seasons are due to reasons all connected to this mis-alignment 7. The rotation of the Solar System bodies is to be understood in the context of Solar System formation from collapse of a gas cloud 103
  104. lecture 1 overview - coordinates reading Kaler Chapter 2-3 by

    next class. Many of the concepts we went through are developed in the course of Chapter 2, so you must have already done some of the work! Look up times: http://www.astronomy.ohio-state.edu/~pogge/Ast161/Unit2/ time.html Wikipedia is a good resource for the scientific method: start at http://en.wikipedia.org/wiki/Falsifiability and if you are interested follow the links, to Positivism, to Probabilistic or non-probabilistic induction, etc... Read the first outdoors lab: we may go out this week! 104
  105. lecture 2 the scientific method - earth’s motion 105

  106. lecture 2 the scientific method - earth’s motion 106